Device for gripping optical fibers
An optical fiber gripping device comprises a sheet of material having first and second members hingedly attached at a first end of each of the members. A gripping region is also provided and includes first and second gripping portions disposed on first and second inner portions of each of the members. The sheet of material further includes at least one slot to define separate clamping zones along a length of the gripping region.
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The present application is a continuation-in-part of U.S. application Ser. No. 10/668,401 (Atty. Dkt. No. 58973US002), filed on Sep. 23, 2003, now pending, and incorporated by reference in its entirety.
BACKGROUND OF THE INVENTION1. Field of the Invention
The present invention is directed to a device for gripping optical fibers. In particular, the present invention is directed to a device for gripping optical fibers having a protective coating, such as a polymer-based coating.
2. Related Art
Mechanical devices for splicing optical fibers for the telecommunications industry are known. For example, U.S. Pat. No. 5,159,653 describes an optical fiber splice that includes a sheet of ductile material having a focus hinge that couples two legs, where each of the legs includes a V-type groove to optimize clamping forces for conventional glass optical fibers. The described splice device has been commercially incorporated in the FIBRLOK II™ mechanical fiber optic splice device, available from 3M Company, of Saint Paul, Minn. In addition, U.S. Pat. No. 5,337,390 describes an adhesiveless connector, with a connector body and ferrule attached to one another, with a mechanical gripping element residing in the connector body to hold an optical fiber in place. The gripping element described therein is engageable by moving a plug in a direction transverse to bores formed in the connector body and ferrule. The described connector has been commercially incorporated in the CRIMPLOK™ fiber optic connector, available from 3M Company, of Saint Paul, Minn. Conventional devices are also described in U.S. Pat. Nos. 4,824,197; 5,102,212; 5,138,681; and 5,155,787.
These conventional products typically utilize deformable v-groove technology to achieve fiber alignment and retention. This technology involves the displacement of element material, conventionally a ductile or malleable material such as aluminum, by the glass optical fiber. Glass is robust when exposed to compressive forces and can accomplish the displacement of the soft aluminum v-groove without compromising its own structure.
However, other fiber compositions are useful for optical applications. For example, U.S. Pat. No. Re. 36,146 describes an optical fiber element (referred to herein as “GGP fiber”) that includes a protective coating affixed to the glass optical fiber that remains on the glass optical fiber during splicing or connectorization. This protective coating, which can protect underlying layers from abrasion, cracking, and mechanical damage, can comprise a polymer-based coating that does not have the robustness of glass when exposed to compressive forces.
SUMMARY OF THE INVENTIONAccording to a first aspect of the present invention, an optical fiber gripping device comprises a sheet of material having first and second members hingedly attached at a first end of each of the members. A gripping region is also provided and includes first and second gripping portions disposed on first and second inner portions of each of the members. The sheet of material further includes at least one slot to define separate clamping zones along a length of the gripping region.
According to another aspect of the present invention, an optical fiber splice includes a sheet of material having first and second members hingedly attached at a first end of each of the members. A gripping region is provided that includes first and second gripping portions disposed on first and second inner portions of each of the members. The sheet of material further includes at least one slot to define separate clamping zones along a length of the gripping region, where a first clamping zone includes a splicing region and a second clamping zone includes a buffer clamping region. The first clamping zone imparts a first amount of stress to a fiber inserted in the gripping region, and the second clamping zone imparts a second amount of stress to the fiber, where the first amount of stress can be different from the second amount.
The above summary of the present invention is not intended to describe each illustrated embodiment or every implementation of the present invention. The figures and the detailed description which follow more particularly exemplify these embodiments.
BRIEF DESCRIPTION OF THE DRAWINGSThe present invention will be further described with reference to the accompanying drawings, wherein:
While the invention is amenable to various modifications and alternative forms, specifics thereof have been shown by way of example in the drawings and will be described in detail. It should be understood, however, that the intention is not to limit the invention to the particular embodiments described. On the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the scope of the invention as defined by the appended claims.
DETAILED DESCRIPTION OF THE EMBODIMENTS
In
The dimensions of sheet 11 may vary considerably depending upon the application. Gripping device 10 can be formed from a sheet 1I1 of deformable material, preferably a ductile metal such as aluminum. An exemplary material is an aluminum alloy conventionally known as “3003”, having a temper of 0 and a hardness on the Brinnell scale (BHN) of between 23 and 32. Another acceptable alloy is referred to as “1100”, and has a temper of 0, H14 or H15. Acceptable tensile strengths vary from 35 to 115 megapascals. Other metals and alloys, or laminates thereof, may be used in the construction of sheet 11. Such metals include copper, tin, zinc, lead, indium, gold and alloys thereof. In addition, a polymeric material, clear or opaque, may be used for sheet 11. Suitable polymers include polyethylene terephthalate, polyethylene terephthalate glycol, acetate, polycarbonate, polyethersulfone, polyetheretherketone, polyetherimide, polyvinylidene fluoride, polysulfone, and copolyesters such as VIVAK (a trademark of Sheffield Plastics, Inc., of Sheffield, Ma.).
With further reference to
For example, gripping device 10 may be preloaded in the folded state (although not in the closed, engaging state) in an optical splice connector body in the manner described in U.S. Pat. No. 5,159,653. Such a splice connector body can include a base and a cap. As the cap is moved from an open position to a closed position, two cam bars can slide over legs 12 and 14, urging them toward one another. In an exemplary embodiment, rounded edges along the outside surface of legs 12 and 14 can facilitate a camming action.
In one embodiment of the present invention, both of the members or legs have a gripping region that respectively comprise gripping portions or grooves 22 and 24 on the inside surface of sheet 11. In an exemplary embodiment, the gripping portions are formed in a pre-grooving process, as described in further detail below. The gripping portions or grooves 22 and 24 are configured to provide mechanical compressive forces that are uniformly applied to the outer diameter of a fiber, such as a protective coated fiber. Such substantially evenly distributed compressive forces can help ensure one or more of the following: coating integrity, coating reliability, optical performance (e.g., optimal axial alignment between two fibers held in the device), and mechanical fiber retention for the lifetime of the device (e.g., splice or connector).
In exemplary embodiments, grooves 22 and 24 are each substantially semi-circular in shape and are generally parallel with hinge region 16, and equidistant therefrom. In some applications, it is not necessary for the grooves that comprise gripping portions 22 and 24 to extend the full length of sheet 11. For example, as shown in
Protective-coated optical fiber 50, for example, can include a glass core 52, a glass cladding 54, a protective coating 56, and a layer 58. In a conventional GGP fiber, such as the embodiments described in U.S. Pat. No. Re. 36,146, layer 58 is removed and the protective coating 56 remains affixed to the glass fiber (core/clad) during connectorization. In this example, the outer diameter of the protective coating 56 is about 125 μm, where the layer 56 has a thickness of about 12.5 μm, surrounding about a 100 μm diameter glass core/clad. As described below, fibers having protective coatings and outer diameters of greater than or less than 125 μm can be utilized with the present invention. In addition, as will be apparent to one of ordinary skill in the art given the present description, the devices and methods of the present application can be utilized to grip, splice, and/or connect alternative optical fibers, including conventional glass-based fibers, POF (Plastic Optical Fiber), and TECS (Technically Enhanced Clad Silica) fiber. These fibers may have several standard diameters (including buffer coatings) of about 125 μm (with or without a buffer coating being removed), 250 μm outer diameter, and/or 900 μm outer diameter, as well as nonstandard diameters in between 125 μm and 900 μm, and larger.
Referring now to
As a comparison,
For these conventional v-groove based products, if a protective-coated fiber (e.g., having a polymer-based coating) is inserted in gripping region 25, the protective coating can crack under the compressive loads, either on a splice or under later temperature cycling, thereby degrading connectivity and/or optical performance. Further, concentrated or localized forces on a protective coating could generate fiber misalignment over time.
As illustrated in
A process for forming the gripping region of the gripping device is referred to herein as pre-grooving. In an exemplary embodiment, this process utilizes a precise, predetermined diameter pin that is harder than the material comprising the gripping portion. The pin is inserted in the gripping region in a predetermined position. The device 10 is then closed to a predetermined position to form the substantially semicircle shapes of gripping portions 22 and 24. This pre-grooving process can ensure precise and reliable alignment of the semi circular grooves because variations in the hinge region 16 may occur during hinge folding. With conventional processes used to fold legs 12 and 14 about the hinge region, offsets of about 0.001″ to about 0.002″ can occur. Thus, the pre-grooving process can maintain optimal alignment between legs 12 and 14.
An exemplary pre-grooving process is shown in
In an exemplary embodiment, a precise diameter pin is used to create the substantially semicircular gripping portions. For example, a pin that has an outer diameter that is the same or slightly larger than the outer diameter of the fiber to be gripped can be utilized. For pins having a smaller diameter than the outer diameter of the fiber, an increase in stress points may occur. If the pin diameter is too much larger than the fiber outer diameter, then stress may be concentrated only on, e.g., the 3 o'clock and 9 o'clock positions of the fiber, relative to a front end view of the fiber. This situation may result in poor fiber-to-fiber alignment and/or higher insertion loss in splicing applications.
In addition, the dimension selected to close the gripping device around the pre-groove pin can influence the degree of stress that is imparted onto the fiber. As the inventors have determined, the greater the difference in dimensions between the final pre-groove dimension, and the closed/engaged dimension of the gripping device, the greater the stress that can be imparted on the fiber.
In the exemplary embodiment of
In one example, a steel pre-groove pin having an outer diameter of 0.0049″ (+0.000040″/−0.0″ tolerance) was utilized. The pin was placed in the gripping region, and the gripping device was placed in a closed pre-groove position of 0.054″ (corresponding to the X2 distance). The pin was removed, resulting in semicircular shaped gripping portions. In this example, the X1 distance was 0.64″, the Y1 distance was 0.058″, and the Y2 distance was 0.050.
According to another embodiment of the present invention, the gripping device can be tailored to impart a more gradual stress onto the outer diameter of the fiber.
According to another embodiment of the present invention, a fiber gripping/splicing/connecting device can be utilized for adhesiveless connector applications, such as in connection with CRIMPLOK™ fiber optic connectors, described above. For example,
Devices using the geometry described above for the gripping region can also be utilized in remateable connecting applications.
In one application of the above described fiber gripping devices, these devices can be utilized to form a connection or splice using protective coated optical fibers, for example a GGP fiber to GGP fiber splice and a GGP to non-GGP fiber splice. Referring back to
Tests were also performed on gripping devices according to the present invention that were used to hold GGP to GGP splices, GGP to glass (SMF—manufactured by Coming Inc., of Corning N.Y.) splices, and SMF to SMF splices. All fibers had an outer diameter of about 125 μm. Regarding initial fiber retention ability, GGP to GGP splices (12 total), GGP to glass (SMF) splices (12 total), and SMF to SMF splices (12 total) each had the average tensile force to failure results of greater than 2 lbs.
In addition, a fiber retention test was made using eight GGP fiber splices made in a gripping device according to the present invention under accelerated environmental conditions. In this test, fiber retention was measured after placing the splices in a chamber where the temperature and humidity were maintained at 85 degrees C. and 95% relative humidity, respectively, for ten days. Also, the gripping portions of the gripping device contacted about 300-310 degrees of the perimeter of the 125 μm GGP fiber being held. All eight GGP fiber splices exhibited fiber retention of 3.3 lbs or greater. As a comparison, ten 125 μm GGP fiber splices were made using v-groove splice devices under these same accelerated environmental conditions. None of the v-groove GGP splices exceeded 1 lbs. fiber retention under these conditions.
As described above with respect to
For example,
Device 170 is similar to the device shown in
These configurations allow different levels of stress to be imparted on the fiber that is located in each zone. In exemplary embodiments, a light stress can be utilized for the precise alignment of two fibers in the splicing zone, while an increased stress can be imparted onto the fiber in the clamping zone to increase fiber retention. The single and double slot arrangements can offer differing strengths, depending on the application.
As fiber optics are deployed deeper into the metro and access areas of a network, the benefits of such mechanical interconnection products can be utilized for Fiber-To-The-Home/Desk/Building/Business (FTTX) applications. The devices of the present invention can be utilized in installation environments that require ease of use when handling multiple splices and connections, especially where labor costs are more expensive.
The present invention should not be considered limited to the particular examples described above, but rather should be understood to cover all aspects of the invention as fairly set out in the attached claims. Various modifications, equivalent processes, as well as numerous structures to which the present invention may be applicable will be readily apparent to those of skill in the art to which the present invention is directed upon review of the present specification. The claims are intended to cover such modifications and devices.
Claims
1. An optical fiber gripping device, comprising:
- a sheet of material having first and second members hingedly attached at a first end of each of the members; and
- a gripping region that includes first and second gripping portions disposed on first and second inner portions of each of said members, wherein the sheet of material further comprises at least one slot to define separate clamping zones along a length of said gripping region.
2. The optical fiber gripping device according to claim 1, wherein a first clamping zone imparts a first amount of stress to a fiber inserted in said gripping region, and a second clamping zone imparts a second amount of stress to the fiber, said first amount different from said second amount.
3. The optical fiber gripping device according to claim 1, wherein the at least one slot comprises a first slot cut through the first member at a first location along said gripping region and a second slot cut through the first member at a second location spaced apart from the first location, wherein the region between the first and second slots forms an inner clamping region.
4. An optical fiber splice device, comprising:
- a sheet of material having first and second members hingedly attached at a first end of each of the members; and
- a gripping region that includes first and second gripping portions disposed on first and second inner portions of each of said members, wherein the sheet of material further comprises at least one slot to define separate clamping zones along a length of said gripping region, wherein a first clamping zone includes a splicing region and a second clamping zone includes a buffer clamping region.
5. The optical fiber splice device according to claim 4, wherein the first clamping zone imparts a first amount of stress to a fiber inserted in said gripping region, and the second clamping zone imparts a second amount of stress to the fiber, said first amount different from said second amount.
6. The optical fiber splice device according to claim 4, wherein the sheet of material comprises first and second slots spaced at different locations along the length of said gripping region.
7. The optical fiber splice device according to claim 4, wherein the first and second gripping portions each comprise a semicircular shape.
8. The optical fiber splice device according to claim 4, wherein at least one of the first and second gripping portions comprises a v-groove.
9. The optical fiber splice device according to claim 4, wherein the sheet of material includes a first slot located on the first member and a second slot located on the second member, opposite the first slot.
Type: Application
Filed: Mar 2, 2004
Publication Date: Mar 24, 2005
Applicant:
Inventor: James Carpenter (Austin, TX)
Application Number: 10/790,926